Electric communication network



Nov. 1, 1938. H. R ALLENSWORTH 2,134,691

ELECTRIC COMMUNICATION NETWORK Filed July 13, 1957 INVENTOR HARRY R ALLENSWORTH BY 1%! 29M ATTORNEY Patented Nov. 1, 1938 UNITED PATENT OFFICE 2,134,691; ELECTRIC COMMUNICATION NETWORK Columbus, Ohio weenie-aw 2 1937; SW -3 .3

' 9.1Claimsa (01. 179-81) This invention relates to a new and improved electric communication network and" more pare ticularlyto a communication network", or that part of a communication networkcomprising a 5 telephone transmitter, a telephonereceiver, a transformer (induction coil) "and two condensers (capacitors) and has for its object a n w and improved combination of these elements in, an electric network, functioningby' means of electromotive force,'the source of which electroino tive force is external to the electric network comprising the said telephone transmitter, receiver, transformer andcondensers.

A conventional telephone network comprises a three winding transformer, atransmitter, condenser and an inductively coupled receiver together with suitable switchesand signaling and calling devices. The condenser and two windings of the transformer are inyserie'se-one of whichtwo windings being connected acrossthe terminals of thetransmitter, directly on Jone side and in series with the condenser on the other; The third winding together with the receiyer-in series form an inductively coupledfsecondary circuit,

To my knowledge there has not been prior to this inv-entionan electric communication net:- work, telephonic or otherwise, comprising four transformer windingsthree of said windings being primary to the" fourth-a'telephonetransmitter, a telephone receiver, and two condensers; saidnetwork being divided intoftwo parallel circuits bridged by one of said condensers. V

The invention will be best understood from a consideration of the following detailed description taken in connection with the] accompanyingdrawing forming a part of this application; with the understanding, however, that theinvention is not confined to the one practical ap- 40 plication herein selected forpurposes' of illus tration nor is the invention confined to any strict conformity with theshowing of, the drawing which may be changed or modifiedso'long as such changes and/ormodifica'tions mark no material departure from the salient features of the inventionwithin the scope ofthe appended claims.

The accompanying drawing is a schematicdee lineation, by means of conventional symbols, of

a useful and practical application. of the invention in the form ofa telephone subscribers sta tion network comprising eight members or, parts to wit; a sourcejof electromotive fOrce-hererrie resented'by two sides of a line, Ll and. L2 a telephonetransmitter T; transformer] windings Pl, P2 andP3; bridgingcondenser C; series condenser Cl and an inductively coupled secondary circuit comprising transformer winding S and telephone receiver R. Also are shown, by means of conventional symbols, calling device CD with associated shunt contacts SH, polarized ringer or hell Band hook switch HS with associated contact springs 8 and 9. Calling device CD with associated shunts, ringer. B and hook switch HS are'not, per se, a part of the invention. Calling device CD with associated shunt contacts is shown for the purpose of' revealing certain important characteristics of the network. Hook switch HS and polarized ringer B are shown for the purpose of explaining the function and action of contact springsfl and 9,.

The source of electromotive force LI, and L2 may be, a telephone line terminating in a coinmon battery telephone switchboard or other common battery switching mechanismit may be a circuit to another telephone not connected to or with an exchange system, in which case electromotive force isimpressed on the circuit at some convenient point external to the network herein described -it may be a telegraph or other signal circuit-it may be any suitable electric circuit which it may be practicable to employ for telephonic purposes by means of the network herein described;

Electromotive forceffrom the source, LI and L2- is impressed on the circuit or network at points 4 and 5 causin'g electric' current to flow through P2, T. The divided circuit 4, Pl, Ci, P3,, 5; 4, P2, T, 5 is bridged by a condenser C at points 6 and 1.

All four transformer windings Pl,,P2, P3 and S are on the same magnetic core.

The operation of this circuit or network, dUI-r ing speech transmission is as follows.

The line circuit Ll, L2 which supplies direct current from a central oflice battery, or other suitable source, divides into two parallel circuits at points 4 and 5; one of the two parallelcirw cuitscomprising transmitter T andPZ inseriesthe other, comprising Pl, CI andv P3 in series. Battery flows in that branch of the divided cir cuit comprising P2, T; the other branch of the divided circuit being.openl to: direct current because of condenser Cl being in series withPl andPB.

Another circuit, local to the network, in the form here, shown, comprises transmitter T, condensers C and Cl and transformer windingv P3. It should be noted however, that the position of condenser Cl is not fixed byeither this} descriptionor the drawingherein, Condenser CI may betplaced at any convenient andpractical point inthat branch of the, dividedcircuitdefined by 4, Pl, 1, P3, 5.

When the transmitte'nT functions invr'esp'onse.

to sound waves, corresponding potential undulations are produced directly in the line through transmitter T and winding P2. Condenser C is connected across the terminals of transmitter T directly on one side and through condenser Cl and winding P3 on the other. Condenser C charges and discharges due to varying potential drop across transmitter T. This causes P3 and PI to function as an auto transformer in which circumstance PI is, secondary to P3. The current flowing in the said local circuit divides at the point I; part flowing through Cl, P3 and part through Pl. Thus the inductive effect of P3 on S is neutralized more or less depending on the relative proportions of PI, P2 and P3; an effect known to the art as anti-sidetone. Also, Pl functions as an inductively coupled feed back on P2 producing improved booster char acteristics in the network. 'As herein before stated, Cl may or may not be comprised in said local circuit. 7

When the transmitter at the distant station functions, potential undulations from LI and L2 are impressed at points 4 and 5 which causes undulatory current to flow in P2, T and corresponding alternating current to flow in PI, Cl, P3 in which circumstance Pl, P2 and P3 are primary to S and corresponding alternating FL is induced in S causing alternating current to flow in S and receiver R.

When calling device CD is operatedass ociated shunt contacts SH close, shunting transmitter T and transformer winding S. Inasmuch as S is secondary to PI, P2 and P3-shunting S during the operation of CD lessens the impedance of PI, P2 and P3 to current impulses produced by Condenser C is shown bridging the network at points 6 and I. Condenser Cl is shown in series relation with PI and P3; Itis not necessary to employ two separate condensers inv the network. C and CI may be, in some instances,two sections of a dual condenser.

When hook switch HS is down contact springs 8 and 9 put C in series with B across Li and L2.

When HS is up C, by means of 8 and 9, bridges the network at points 6 and l as is shown.

Thus the said eight members or parts as assembled and combined in the invention effect the following improved results over other such networks; lessened impedance to dialing, impulses, improved booster effect together with anti-sidetone characteristics and high fidelity transmission and reception.

What is claimed is:

' 1. An electric communication network comprising two parallel circuits, one of the two parallel circuits comprising a telephone transmitter in series relation with one winding of a transformer having four windings, the other of the said parallel circuits comprising two of said windings and a condenser in series relation therewith and a condenserjbridging saidcircuits from a point between the transmitter and transformer winding in one of said parallel circuits to a point between the two transformer windings in the other of the said parallel circuits.

' 2. An electric communication network comprising two parallel circuits, one of the two parallel circuits comprising a telephone transmitter in series with one winding of a transformer having four windings and the other of the said parallel circuits comprising two of said windings and a condenser in series relation therewith, the said three windings in the said parallel circuits being primary to said fourth'winding.

3. An electric communication network comprising two parallel circuits, one of the said parallel circuits comprising a telephone transmitter in series with one winding of a transformer having four windings; the other of the two parallel circuits comprising two of said windings and a condenser in series, and atelephone receiver in series with said fourth winding forming an inductively coupled circuit, secondary to the three said transformer windings.

4. An electric communication network in which both anti-sidetone and booster characteristics are incorporated by dividing the said circuit or network into two parallel circuits, one of which parallel circuits comprises a telephone transmitter in series with one winding of a transformer having four windings, the other of which parallel circuits comprises two of said windings and a condenser in series relation therewith, and a condenser bridging said circuits at points of approximately equal potentials.

5. An electric communication network comprising two parallel circuits, one of the two parallel circuits comprising a telephone transmitter in series with one winding of a transformer having four windings, the other of the said parallel circuits comprising two of said windings and a condenser in series, the total impedance offered by said parallel circuits to pulsating current set up in said network being reduced by short circuiting a transformer winding said short circuited transformer winding being secondary to the three said transformerwindings comprised in the said two parallel circuits.

6. An electric communications network comprising a transformer having four separate windings, three of said windings being primary to the fourth, two parallel circuits, a condenser bridging said parallel circuits and a condenser in one of said parallel circuits in series with two of the aforesaid windings.

7. An electric communication network comprising two parallel circuits and a transformer having four windings, one of said parallel circuits comprising a telephone transmitter and one of said transformer windings in series relation therewith, the other of the two parallel circuits comprising two of said windings and a condenser in series relation therewith, said parallel circuits comprising a local circuit including said telephone transmitter.

8. An electric communication network comprising two parallel circuits and a transformer having four windings, one of said parallel circuit-s comprising a telephone transmitter and one of said transformer windings in series relation therewith, the other of the two parallel circuits comprising two of said windings and a condenser in series relation therewith, a condenser bridging said parallel circuits; said parallel circuits comprising a local circuit including said telephone transmitter and said bridging condenser.

9. An electric communication network comprising two parallel circuits and a condenser bridging said circuits, one of the two parallel circiuts comprising a telephone transmitter in series with one winding of a transformer having four windings, and one of said parallel circuits comprising a condenser and two of said windings in series, the three windings in the said parallel circuits being primary to a fourth connected directly to a telephone receiver.

' HARRY R. ALLENSWORTH. 

